A Light Emitting Diode (LED) is a semiconductor device that converts electricity into ultraviolet rays, visible rays, and infrared rays through characteristics of a compound semiconductor, and is mainly used for appliances, remote controllers, and large billboards.
A high-brightness LED light source is used for a lighting device. Since the LED has very high energy efficiency, low replacement cost (due to its long lifecycle), strong resistance to vibration or impact, and no need for toxic substances such as mercury, it replaces incandescent light bulbs or fluorescent lamps in terms of energy conservation, environmental protection, and cost reduction.
Moreover, the LED is very advantageous for a light source of large and medium sized Liquid Crystal Display (LCD) TVs and monitors. Compared to a Cold Cathode Fluorescent Lamp (CCFL), the LED has more excellent color purity and less power consumption, and is easily miniaturized. Therefore, a prototype using the LED is mass-produced currently, and its research is in progress actively.
Recently, several techniques producing white light with a blue LED by using a Quantum Dot (QD) that emits red light and green light as a fluorescent substance are introduced now. This is because white light generated using the QD has high brightness and excellent color reproduction.
However, even when the above techniques are applied to an LED backlight unit, the need for research to reduce possible light loss and improve color uniformity is still necessary.